The upper Androscoggin and upper Kennebec rivers are "hot spots" for mercury pollution, according to two studies published this month in BioScience, a peer-review journal.

The studies identified five northeastern regions with high mercury levels in fish and birds. The hot spots include the Adirondack Mountain region in New York, the upper Connecticut River in New Hampshire and Vermont, the lower Merrimack River in New Hampshire and Massachusetts, central Nova Scotia and the upper Androscoggin and Kennebec rivers.

In one of the most polluted regions - central Nova Scotia - researchers found that 90 percent of common loons had high mercury levels.

"That's an extreme," said David Evers, director of the BioDiversity Research Institute in Gorham and a lead author of one of the studies.

The Androscoggin River region wasn't that polluted, Evers said. But mercury levels in local fish and birds were still high enough to land it on the list.

Most of the mercury seems to come from out of state, carried in rain, snow or air, Evers said. The Androscoggin and Kennebec river reservoirs - both situated geographically on or near Maine's western borders - aggravate the situation.

Although he called the mercury levels "problematic," Evers was careful not to raise an alarm. While pregnant women and children shouldn't eat fish from the mercury tainted rivers, he said, others can safely eat it once in a while.

"People just need to be aware of the risks," he said.

Local environmental activists weren't surprised by the mercury studies.

Neil Ward, program director for the Androscoggin River Alliance, called the reports "a wake-up call."

"I'm glad to see someone has pointed a finger, especially at the Androscoggin," he said.

Matt Prindiville, policy advocate for the Natural Resources Council, agreed.

"This highlights that the continued pollution of air and water from coal-fired power plants needs to stop," he said.

Maine has no coal-fired plants and has lead the nation in getting rid of products that contain mercury, such as some thermometers. But, Prindiville said, other states' emissions affect Maine. They arrive here by riding on prevailing westerly winds. His group is one of several suing the Environmental Protection Agency to change mercury pollution rules, he said.

While the studies did highlight pervasive pollution, they offered some hope. When mercury levels were cut, fish and birds recovered quickly.

"That's really good news," Evers said.